Our initial DFT-MD simulations were run concurrently for 24 hours on four nodes each of a Linux cluster, with thirty-six 2.1 GHz Intel Xeon E5-2695 v4 cores and 128 gigabytes memory per node. This represented a usage of over 20,000 CPU hours. Generation of SK tables for chosen values of \(R_\psi \)  and \(R_n\)  run were on a single CPU and required approximately one hour of wall-clock time for each set. blackAgain, hydrogen compression radii were held at miomod-hh-0-1 values. blackFor this effort, we choose to use a `global' compression radius for Ti, where all orbitals use the same confinement radius. This is consistent with previous Ti related parameterizations available for download[1]}, [2]}, [3]}, all which use the same confinement radius for s, p, and d orbitals. There is some possibility that separate confinement for the vacant 4p orbital could yield improved accuracy[4]}, which is the subject of future work. Calculation of the \(E_\mathrm {Rep}\)  training set was run using twelve OpenMP threads, requiring \(\sim \) 30 minutes. Solving the linear least-squares problem for a single ChIMES parameterization required less than one minute on a single CPU in all cases, allowing for extremely rapid screening of different sets of parameters. All minimum and cutoff radii for the ChIMES \(E_\mathrm {Rep}\)  were set to include the first coordination shell sampled in our training set, only: \(2.5 \le r_{TiTi} \le 3.5\)  \(\,\) Å\(\,\)  and \(1.5 \le r_{HTi} \le 2.5\)  \(\,\) Å\(\,\) . We use values of \(\lambda _{TiTi} = 3.0\,\) Å\(\,\)  and \(\lambda _{HTi} = 2.0\,\) Å\(\,\)  for the Morse-like coordinate transforms. H-H repulsive interaction were not sampled in our training set and were thus takes from the miomod-hh-0-1 parameter set.
